Effect of polypeptide CH50 on macrophage activationin vivo and antitumor function

The main features of CH50, a recombinant polypeptide of human fibronectin, activating macrophagesin vivo and its anti-tumor function were investigated. After injection of CH50 and (or) transfection of IFN-γ genein vivo, several kinds of factors produced by macrophages were determined and the growth of tumorin vivo was measured. CH50 could enhance the production of such factors as NO, TNF and IL-1 by macrophages, but the activation of macrophages was relatively slow when CH50 was used in vivo alone. CH50 and IFN-γ could synergistically activate macrophages rapidly in vivo no matter whether the injection of CH50 or the transfection of IFN-γ gene was performed first. Injection of CH50 alone inhibited the formation of tumor nodes in a dose-dependent manner. Low dose of CH50 could strongly inhibit the formation of tumor nodes less than 1 mm, while high dose of CH50 could inhibit those more than 1 mm. A stronger inhibition on the growth of tumor in vivo was obtained by the synergistic effect of CH50 and IFN-γ. CH50 and IFN-γ, as double-signal factors for activation of macrophages, will be potentially useful in tumortherapy.